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Questions and Answers
Explain how kinetic energy changes when a moving vehicle comes to a stop.
Explain how kinetic energy changes when a moving vehicle comes to a stop.
The kinetic energy of the vehicle is converted into thermal energy due to friction between the wheels and brakes.
What is the formula for gravitational potential energy and what do each of its variables represent?
What is the formula for gravitational potential energy and what do each of its variables represent?
The formula for gravitational potential energy is $E_p = mgh$, where $m$ is mass in kg, $g$ is the gravitational field strength (9.8 m/s²), and $h$ is height in meters.
Describe the process of energy transfer involved when a ball rolls and hits a wall.
Describe the process of energy transfer involved when a ball rolls and hits a wall.
When the ball hits the wall, some of its kinetic energy is transferred as sound energy.
Define power and its relationship to energy transfer.
Define power and its relationship to energy transfer.
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How does the concept of specific heat capacity relate to thermal energy changes in a substance?
How does the concept of specific heat capacity relate to thermal energy changes in a substance?
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How does lubrication in a motor contribute to energy efficiency?
How does lubrication in a motor contribute to energy efficiency?
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Explain the relationship between thermal conductivity and energy loss in building materials.
Explain the relationship between thermal conductivity and energy loss in building materials.
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Define efficiency in the context of energy systems and state how it can be improved.
Define efficiency in the context of energy systems and state how it can be improved.
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What are the key differences between renewable and non-renewable energy sources?
What are the key differences between renewable and non-renewable energy sources?
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Discuss the reliability challenges associated with renewable energy sources.
Discuss the reliability challenges associated with renewable energy sources.
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Study Notes
Energy Stores
- A system's energy storage changes when the system changes, e.g., a ball hitting a wall.
- Kinetic Energy (Ek): Ek = 1/2 * m * v², where m is mass and v is velocity. Stored in moving objects.
- Elastic Potential Energy (Eel): Eel = 1/2 * k * e², where k is spring constant and e is extension. Stored in stretched objects.
- Gravitational Potential Energy (Egp): Egp = m * g * h, where m is mass, g is gravitational field strength (9.8 m/s²), and h is height. Stored in objects above the ground, due to their position.
- Specific Heat Capacity: Energy needed to raise the temperature of 1 kg of a substance by 1°C or 1K. Energy = mass × specific heat capacity × temperature change (ΔT).
Power
- Power is the rate at which energy is transferred or work is done.
- Power (P) = Energy transferred (E) / Time (t) = Work done (W) / Time (t)
- Units: Watts (W) = Joules (J) / Second (s)
- Higher power means faster energy transfer.
Energy Transfers
- Energy can be transferred, stored, or dispersed, but cannot be created or destroyed.
- Dissipated energy is less useful, often as heat.
- Ways to reduce energy waste include lubrication and thermal insulation.
Thermal Conductivity
- Thermal conductivity describes how easily heat travels.
- Higher conductivity = faster heat transfer. This is crucial for insulating buildings.
Efficiency
- Efficiency is the ratio of useful work done to total energy input, usually expressed as a percentage.
- Efficiency = (Useful energy output / Total energy input) * 100% = (Useful power output / Total power input) * 100%
Energy Resources
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Non-renewable: Fossil fuels (coal, oil, gas), nuclear fuel. Finite resources; cannot be replenished.
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Renewable: Biofuel, wind, hydro-electricity, geothermal, tidal, solar, water waves. Can be replenished.
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Renewable energy is becoming more important due to the finite lifetime of fossil fuels.
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Renewable energy development is important because of the environmental and finite characteristics of fossil fuels.
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Extraction of energy (fossil fuels, wind/solar) has environmental impacts.
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Energy use patterns and trends (historical reliance on fossil fuels)
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Development of renewable energy technology is necessary to meet current and future energy demands, but presents challenges (e.g. political, social, ethical, economic considerations).
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Description
Explore the concepts of energy storage, power, and transfers in this quiz. Understand kinetic energy, elastic potential energy, gravitational potential energy, and the specifics of power calculations. Test your knowledge on how energy changes within different systems.
